The invention relates to the field of tight connections for tubular components, used in particular for hydrocarbon or the like wells, for example geothermal wells. During use, the connections are subjected to large compressive and tensile stresses and they must not come apart. The connections are also subjected to internal or external fluid pressure stresses, and bending or torsional loads, which may be in combination, of an intensity that may fluctuate and at frequencies that are likely to vary. The tightness must be guaranteed despite the loads and despite harsh on-site conditions.
For a number of years, tubes have been subjected in situ to diametral expansion causing permanent plastic deformation. The connections must remain operational after plastic deformation by diametral expansion which they undergo along with the tubes. It is desirable that following plastic diametral expansion, the threaded connections should hold, retaining the essential properties for which they are valued, in particular mechanical tension/compressive behaviour, with or without internal or external overpressure, as well as tightness.
The Applicant's patent FR-2 834 326 proposes a connection provided with two tongues engaging respectively in concavities with an S shaped profile with a radial clearance at the upper and lower portions of the “S”. Contact at the end of makeup is made between the substantially radial surfaces and the substantially cylindrical surfaces of the tongues, said substantially cylindrical surfaces facing each other. During diametral expansion, one of the tongues is tipped towards the other, reinforcing the tightness of the connection.
The invention has improved the situation, in particular as regards tightness in the case in which the expansion operations are operations with a high degree of expansion (in particular more than 15%), or indeed compressive expansion operations.
The expandable threaded connection may be used in the exploration or working of hydrocarbon or geothermal wells. The expandable connection comprises a first tubular component comprising a male end comprising a first and a second threaded zones disposed on an external peripheral surface and an insertion region provided between the first and second threaded zones. The insertion region is provided with a first annular tongue comprising a prominent abutment face and a first concavity adjacent to the first tongue and set back therefrom.
The expandable threaded connection comprises a second tubular component comprising a female end comprising a third and fourth threaded zones disposed on an internal peripheral surface and an insertion region provided between said third and fourth threaded zones. The insertion region is provided with a second annular tongue comprising a prominent abutment face, and a second concavity adjacent to the second tongue and set back therefrom. The first and second threaded zones of the male end match the third and fourth threaded zones of the female end for makeup therewith. The threaded zones respectively comprise male and female threads. The first and second tongues are respectively engaged in the first and second concavities in the made up condition, the abutment face of at least one of the first and second tongues being in contact with at least the second or the first concavity. The male end comprises a first surface between the first threaded zone and the first tongue and the female end comprises a second surface between the third threaded zone and the second concavity. In the made up condition, said first and second surfaces define an annular space comprising a zone with a large radial dimension on the first and third threaded zone side and a zone with a small radial dimension on the first tongue and second concavity side. The zone with a small radial dimension is capable of forming a seal by metal-metal contact after expansion. The first tongue bears on the second tongue.
The zone with a large radial dimension promotes deformation of the male end during expansion and facilitates tipping of the first tongue towards the second tongue in order to create a metal-metal seal between said tongues. The zone with a small radial dimension enables to form a metal-metal seal between the first and second surfaces from the start of diametral expansion.